Crankshaft governor



Filed Aug. 5, 193s ,War

C41.. ibi/wwwa Patented Jan. 28, 1941 UNITED STATES CRANKSHAFT GOVERNOR James L. Wall, Washington, Ga., assigner of onehalf to Pratt A. Carter, Washington, Ga.

Application August 5, 1938, Serial No. 223,317

3 Claims.

This invention relates to crankshaft governors generally; and more particularly to crankshaft governors designed for use on steam engines of the piston type.

The main object of the invention is to provide a governor to control the inlet valves of steam engines and adapted to be applied to a crankshaft so as to open `the inlet valve at exactly the same time and in exactly the same relation to a rotating crankshaft to hold the valve open only for the length of the engine stroke required to furnish steam sulcient to carry the load to be driven, and to allow for expansion of the steam throughout thel remainder of the engine stroke after the closing of the valve.

Another object of the invention is to provide governor mechanism constructed for connection to a crankshaft so as to eliminate vibration of the governor Weights and springs.

Still another object of the invention is to provide a governor mechanism adapted to be connected to the crankshaft of an engine to control the operation of the inlet valves of any number of engine cylinders.

Other objects of the invention will become apparent as the detailed description thereof proceeds:

In the drawing:

`Figure 1 is a cross section of a preferred form of governor mechanism, the section being taken on the line I--I of Figure 2;

Figure 2 is a longitudinal section taken on the line 2--2 of Figure l; and

Figures 3, 4 and 5 are geometric diagrams illustrating the geometrical principle involved in a design of the valve operating cam mechanism of the governor.

The governor mechanism comprises a substantially rectangular base plate Ii having a collar 1 extending from one side thereof to fit snugly on a crankshaft 8. The base plate 6 and collar 1 are secured to the shaft 8 by means of a screw 9 screw-threaded radially through the collar 1 to seat yin the recess I0 formed in the periphery of the shaft 8. The collar 1 is cylindrical on its outer surface and larger in diameter than the crankshaft and is mounted on said crankshaft as an eccentric on which is rotatably mounted a cam sleeve II.

The sleeve II has a spur gear I2 formed on one end thereof to mesh with a pair of segmental gears I3 and I4 formed on collars I5 and I6 which are mounted to rotate on pivot bolts I1 and I8 suitably secured to the base plate 6. Weights I9 and 20, formed integral with the collars l5 and I6, respectively, are suitably welded to the adjacent ends of the segmental gears I3 and I4. The diagonally opposite ends of the base plate 6 are provided with brackets 2| and 22 apertured to receive the adjustable screw-threaded rods 23 and 24, respectively, adapted to be held in adjusted position in the brackets 2| and 22 by clamp nuts engaging said rods on opposite sides of the brackets 2| and 22.

A tension spring 25 is secured at one end to l@ the rod 23 and at its other end is suitably secured to a pin 25' projecting axially from the center of the weight 20. Similarly, a tension spring 2B is secured at one end to the rod 24 and at its other end to a pin 26' extending axially 15 from the weight I9. Obviously, the segmental gears 23, 24 and the centrifugal weights I9 and 20 and the spring members must be symmetrically arranged Wth respect to any plane passing y through the axis a of the crankshaft 3. 20

For the purpose of operating an inlet valve V of a steam engine, the sleeve I I is formed With a cam 21 having an arcuate edge 28 adapted to wipe against a roller 29 formed on one end of a lever arm 30 pivoted to rock about a pivot pin 25 3l suitably secured to the framework (not shown) of the engine. A link 32, pivoted at its opposite ends to the lever arm 30 and toone arm of a bell crank 33, rocks the bell crank about thel pivot pin 34 to open the valve V and admit steam 30 to the cylinder of a steam engine. The structural details of this valve operating mechanism form no part of the present invention and is illustrated herein merely for the purpose of eX- plaining the principle of the governor mecha- 35 nism forming the subject matter of this application.

As sho-Wn in Figures 1; 3, 4 and 5 of the drawing, the wiping edge 28 of the cam 21 is an arc of a cylinder having its axis b oiset laterally through the distance w-b in a plane passing through both axes a and b and bisecting the eccentric collar 1 symmetrically. The distance a--b is the lateral offset required to open the valve V to its maximum. 45

In setting out the cam edge 28, and assuming a counter-clockwise rotation of the crankshaft 8, concentric circles C and C are struck from a as center with radii a-c and a-d respectively, the circle C being tangent to the outer surface 50 of the sleeve I I when at rest, and With the points c and d lying in a straight line passing through the line a-b. The radius a-d is equal to the radius af-c plus the throw a--b 0f the eccentric 1.

A tangent c-e is drawn from the point c to intersect the circle C at the point e. With b as center and radius b-e, the arc e-f is struck to intersect the circle C in the point f, through which the arc e-j may be continued to intersect the tangent g-h drawn from the outer surface of the sleeve II parallel to the tangent c-e.

If we consider the point f as a fixed point on the base plate 6, it is evident that the curved surface e-g of the cam 21 must always intersect the circle C at that point f. This means that in all positions of the cam 21, its cam edge 28 strikes the roller 29 to open the inlet valve V at exactly the same time in relation to the angular position of the crankshaft 8 to which the base plate 6 is xed.

The position of the cam 21 at the start of rotation of the crankshaft 8 is shown in Figures 1 and 3. It will be apparent from these figures, that as the shaft 8 rotates, the plate 6 rotates with it, and carries around the cam 21 so that the point on the arcuate edge 28 directly above the imaginary point f on the base plate 6 strikes rst against the roller 29, which then rides along the edge 28 past the point e and along the tangent e-c to the point c, at which point the roller 29 is released. During the remaining part of the rotation of the crankshaft 3, the valve V is closed and the steam is allowed to expand in the cylinder.

As the speed of rotation of the crankshaft increases, the Weights I9 and 2U spread apart by centrifugal force and rotate the sleeve II around the eccentric collar 1, to move the cam 21 into the position shown in Figure 4. From Figure 4, it will be apparent that the cam edge 28 will not strike the roller 29 until it reaches that part directly over the imaginary point j on the base plate 6. The roller 29 will then ride over a smaller portion of the cam edge l23 and around the point e and then along that part of the tangent e-c to the point i, Where the roller becomes released from the cam and the valve V closed.

In Figure 5, the crankshaft is illustrated with the cam mechanism in the position required by maximum speed. In this position the governor mechanism has rotated the cam sleeve I I around the eccentric collar 1 so far as to prevent any contact of the cam 8 with the roller 29.

It is evident that the cam 28 strikes the roller 29 to open the inlet valve at exactly the same time and in exactly the same space relation to the angular position of the crankshaft 8. It is also evident that this` cam construction holds the inlet valve open only for the length of engine stroke required to furnish enough steam to carry the load to be driven, and allows the steam to expand during the remainder of the engine stroke.

This governor mechanism takes the load of opening the valve directly against the cam surface of the sleeve I I, and transfers the load therefrom directly to the eccentric collar 1. Since the eccentric collar is fixed rigidly to the shaft, all vibration of the governor Weights and springs is eliminated.

The eccentric collar 1 and the cam sleeve II may be extended in length as illustrated in Figure 2 of the drawing, and additional cams 21', 21, etc., may be formed on the sleeve I I to be timed with and govern the opening of inlet valves of any number of engine cylinders without adding to the governor mechanism described. In other Words, a single governor'of this type may be used to control all the valves of an engine having any desired number of cylinders.

What I claim is:

1. Governor mechanism comprising a collar adapted to be fixed eccentrically on a crankshaft, a sleeve rotatable on said collar having a cylindrical cam surface co-axial Withvthe axis of said collar, and means to rotate said sleeve on said collar, in accordance with variations in the rotary speeds of the shaft.

2. Governor mechanism comprising a collar having a cylindrical outer surface adapted to be xed as an eccentric to a rotating shaft, a cylindrical sleeve rotatable on said collar having a cam formed thereon with a cylindrical cam surface co-axial with the axis of said collar, and intersecting a straight cam surface tangent to a diameter to the sleeve and means to rotate said sleeve on said collar in accordance With variations in the rotary speeds of said shaft.

3. Governor mechanism' comprising a collar adapted toy be fixed eccentrically on a crank shaft, a sleeve rotatably mounted on the collar and having formed thereon a cam surface comprising a segmental cylindrical surface concentric with the collar and a plane surface perpendicular to the chord of said cylindrical segment and speed responsive means for rotating said sleeve on said collar.

JAMES L. WALL. 

